As human beings age, their bodies tend to deteriorate. It is the task of an engineer to counteract this natural process to ensure that humans can have a high quality of life for as long as possible. A condition that affects a wide range of people is a discomfort and pain in the knee. This is most often caused by osteoarthritis, which occurs when the cartilage in the knee deteriorates causing the bones to rub against each other creating extreme discomfort. It is believed that by 2040, 78 million adults aged 18 years and older in the United States will be diagnosed with osteoarthritis, which makes up roughly a quarter of the projected adult population. An effective solution to alleviating this discomfort is to have a total knee replacement (TKR), and thus the incidences of these surgeries are going to drastically increase.&nbsp;A standard TKR typically involves shaving the ends of the femur and tibia as well as the back of the patella to remove damaged surfaces before implants are inserted on the bones.&nbsp;According to the American Academy of Orthopedic Surgeons, these implants are expected to function properly for 15-20 years in roughly 85% of patients. 90% of patients experience a substantial reduction in pain as a result of the knee replacement.The most commonly used implant method is the cruciate-retaining TKR, which removes the patient’s anterior cruciate ligament (ACL) but preserves the posterior cruciate ligament (PCL) and collateral ligaments. The ACL, however, plays a pivotal role in maintaining the stability of the knee. Unicompartmental Knee Replacements (UKRs) preserve the ACL, but it is estimated that only 10% of surgeons perform this type of knee replacement because they are patient-specific. Preliminary results, however, show that UKRs have provided patients with a shorter stay at the hospital, greater reduction in pain, and greater stability and range of motion. Unfortunately, UKRs also have a higher rate of revision surgeries than their TKR counterparts, which is not beneficial to the patient. However, both methods still have their downsides and need to be improved. Studies show that 27% of all patients having a knee replacement reported hearing grinding, popping, or clicking from their operated knees. These patients were also more likely to report functional limitations and the presence of stiffness and a limp. This, however, was more common in TKRs than in UKRs.It appears that a new design should model aspects of the UKR method. It would be more efficient if the design for a prosthesis allowed proficient ligaments to remain intact. These ligaments would then add more support and stability to the knee, which would theoretically put less stress and strain on the prosthesis itself; thus, increasing its life expectancy. This is particularly important considering that knee replacements are becoming more common in younger age groups, according to a study conducted by the CDC from 2013 to 2015.&nbsp;&nbsp;Having longer lasting prosthetic knees would be beneficial to the patient because it would reduce the number of revision surgeries required to maintain the knee throughout their lifetime. Maintaining the healthy ligaments also provides better range of motion and a more natural feel, which are both criteria that any designer should look to fulfill. The younger patient wants to remain physically active, and modern designs should meet these demands. The goal of this research project is to design a prosthetic knee that is in the patients’ best interests. An optimal design maintains as many natural components of the knee as possible, results in the least amount of recovery time, maximizes the life expectancy of its components, and provides the patient with a repaired knee that feels natural and functions accordingly to their needs.

Design of Knee Prosthesis to Sustain Acl/pcl Ligaments and Alleviate Osteoarthritis

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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